Buildings are using larger windows. For example, the outside of many buildings are made up almost entirely of windows. Many single family homes, as well as high rise condominiums, have large widows or sliding glass doors that take up most of the surrounding wall space. The windows may reflect light from surrounding outside habitat. The birds are fooled by the reflections and fly into the windows causing injury or death. The number of birds that collide into windows has reached epidemic levels with bird mortality rates in the United States due to window collisions reported at around 1,200,000,000 per year.
To prevent bird collisions, some building owners have placed decals on the outside of the windows to disrupt the reflected images. However, these decals have limited success preventing bird collisions. Chances of even moderate success require attaching a large number of the decals to the outside of the window.
The outside of windows may have restricted access. For example, windows may not open or may be located high above the ground. Applying decals on the outside of these windows is difficult, expensive, and/or dangerous. Large numbers of decals placed on the outside of windows also reduce overall building aesthetics and have reduced operating life due to exposure to outside weather conditions.